EFCore 5 新特性 `SaveChangesInterceptor`
EFCore 5 新特性 SaveChangesInterceptor
Intro
之前 EF Core 5 還沒正式釋出的時候有釋出過一篇關於 SaveChangesEvents 的文章,有需要看可以移步到 efcore 新特性 SaveChanges Events,在後面的版本中又加入了 Interceptor 的支援,可以更方便的實現 SaveChanges
事件的複用, 今天主要介紹一下通過 SaveChangesInterceptor
來實現日誌審計
SaveChangesInterceptor
原始碼實現:
public interface ISaveChangesInterceptor : IInterceptor { /// <summary> /// Called at the start of <see cref="M:DbContext.SaveChanges" />. /// </summary> /// <param name="eventData"> Contextual information about the <see cref="DbContext" /> being used. </param> /// <param name="result"> /// Represents the current result if one exists. /// This value will have <see cref="InterceptionResult{Int32}.HasResult" /> set to <see langword="true" /> if some previous /// interceptor suppressed execution by calling <see cref="InterceptionResult{Int32}.SuppressWithResult" />. /// This value is typically used as the return value for the implementation of this method. /// </param> /// <returns> /// If <see cref="InterceptionResult{Int32}.HasResult" /> is false, the EF will continue as normal. /// If <see cref="InterceptionResult{Int32}.HasResult" /> is true, then EF will suppress the operation it /// was about to perform and use <see cref="InterceptionResult{Int32}.Result" /> instead. /// A normal implementation of this method for any interceptor that is not attempting to change the result /// is to return the <paramref name="result" /> value passed in. /// </returns> InterceptionResult<int> SavingChanges( [NotNull] DbContextEventData eventData, InterceptionResult<int> result); /// <summary> /// <para> /// Called at the end of <see cref="M:DbContext.SaveChanges" />. /// </para> /// <para> /// This method is still called if an interceptor suppressed creation of a command in <see cref="SavingChanges" />. /// In this case, <paramref name="result" /> is the result returned by <see cref="SavingChanges" />. /// </para> /// </summary> /// <param name="eventData"> Contextual information about the <see cref="DbContext" /> being used. </param> /// <param name="result"> /// The result of the call to <see cref="M:DbContext.SaveChanges" />. /// This value is typically used as the return value for the implementation of this method. /// </param> /// <returns> /// The result that EF will use. /// A normal implementation of this method for any interceptor that is not attempting to change the result /// is to return the <paramref name="result" /> value passed in. /// </returns> int SavedChanges( [NotNull] SaveChangesCompletedEventData eventData, int result); /// <summary> /// Called when an exception has been thrown in <see cref="M:DbContext.SaveChanges" />. /// </summary> /// <param name="eventData"> Contextual information about the failure. </param> void SaveChangesFailed( [NotNull] DbContextErrorEventData eventData); /// <summary> /// Called at the start of <see cref="M:DbContext.SaveChangesAsync" />. /// </summary> /// <param name="eventData"> Contextual information about the <see cref="DbContext" /> being used. </param> /// <param name="result"> /// Represents the current result if one exists. /// This value will have <see cref="InterceptionResult{Int32}.HasResult" /> set to <see langword="true" /> if some previous /// interceptor suppressed execution by calling <see cref="InterceptionResult{Int32}.SuppressWithResult" />. /// This value is typically used as the return value for the implementation of this method. /// </param> /// <param name="cancellationToken"> The cancellation token. </param> /// <returns> /// If <see cref="InterceptionResult{Int32}.HasResult" /> is false, the EF will continue as normal. /// If <see cref="InterceptionResult{Int32}.HasResult" /> is true, then EF will suppress the operation it /// was about to perform and use <see cref="InterceptionResult{Int32}.Result" /> instead. /// A normal implementation of this method for any interceptor that is not attempting to change the result /// is to return the <paramref name="result" /> value passed in. /// </returns> ValueTask<InterceptionResult<int>> SavingChangesAsync( [NotNull] DbContextEventData eventData, InterceptionResult<int> result, CancellationToken cancellationToken = default); /// <summary> /// <para> /// Called at the end of <see cref="M:DbContext.SaveChangesAsync" />. /// </para> /// <para> /// This method is still called if an interceptor suppressed creation of a command in <see cref="SavingChangesAsync" />. /// In this case, <paramref name="result" /> is the result returned by <see cref="SavingChangesAsync" />. /// </para> /// </summary> /// <param name="eventData"> Contextual information about the <see cref="DbContext" /> being used. </param> /// <param name="result"> /// The result of the call to <see cref="M:DbContext.SaveChangesAsync" />. /// This value is typically used as the return value for the implementation of this method. /// </param> /// <param name="cancellationToken"> The cancellation token. </param> /// <returns> /// The result that EF will use. /// A normal implementation of this method for any interceptor that is not attempting to change the result /// is to return the <paramref name="result" /> value passed in. /// </returns> ValueTask<int> SavedChangesAsync( [NotNull] SaveChangesCompletedEventData eventData, int result, CancellationToken cancellationToken = default); /// <summary> /// Called when an exception has been thrown in <see cref="M:DbContext.SaveChangesAsync" />. /// </summary> /// <param name="eventData"> Contextual information about the failure. </param> /// <param name="cancellationToken"> The cancellation token. </param> /// <returns> A <see cref="Task" /> representing the asynchronous operation. </returns> Task SaveChangesFailedAsync( [NotNull] DbContextErrorEventData eventData, CancellationToken cancellationToken = default); }
為了比較方便的實現自己需要的 Interceptor,微軟還提供了一個 SaveChangesInterceptor
抽象類,這樣只需要繼承於這個類,重寫自己需要的方法即可,實現比較簡單,就是實現了 ISaveChangesInterceptor
介面,然後介面的實現基本都是空的虛方法,根據需要重寫即可
原始碼連結:https://github.com/dotnet/efcore/blob/v5.0.0/src/EFCore/Diagnostics/SaveChangesInterceptor.cs
使用 SaveChangesInterceptor 實現自動審計
簡單寫了一個測試的審計攔截器
public class AuditInterceptor : SaveChangesInterceptor { public override InterceptionResult<int> SavingChanges(DbContextEventData eventData, InterceptionResult<int> result) { var changesList = new List<CompareModel>(); foreach (var entry in eventData.Context.ChangeTracker.Entries<Post>()) { if (entry.State == EntityState.Added) { changesList.Add(new CompareModel() { OriginalValue = null, NewValue = entry.CurrentValues.ToObject(), }); } else if (entry.State == EntityState.Deleted) { changesList.Add(new CompareModel() { OriginalValue = entry.OriginalValues.ToObject(), NewValue = null, }); } else if (entry.State == EntityState.Modified) { changesList.Add(new CompareModel() { OriginalValue = entry.OriginalValues.ToObject(), NewValue = entry.CurrentValues.ToObject(), }); } Console.WriteLine($"change list:{changesList.ToJson()}"); } return base.SavingChanges(eventData, result); } public override int SavedChanges(SaveChangesCompletedEventData eventData, int result) { Console.WriteLine($"changes:{eventData.EntitiesSavedCount}"); return base.SavedChanges(eventData, result); } private class CompareModel { public object OriginalValue { get; set; } public object NewValue { get; set; } } }
實際應用的話還需要根據自己的場景做一些修改和測試
測試 DbContext 示例,這裡使用了一個簡單的 InMemory 做了一個測試:
public class TestDbContext : DbContext { public TestDbContext(DbContextOptions<TestDbContext> dbContextOptions) : base(dbContextOptions) { } public DbSet<Post> Posts { get; set; } } public class Post { [Key] public int Id { get; set; } public string Author { get; set; } public string Title { get; set; } public DateTime PostedAt { get; set; } }
測試程式碼:
var services = new ServiceCollection();
services.AddDbContext<TestDbContext>(options =>
{
options.UseInMemoryDatabase("Tests")
//.LogTo(Console.WriteLine) // EF Core 5 中新的更簡潔的日誌記錄方式
.AddInterceptors(new AuditInterceptor())
;
});
using var provider = services.BuildServiceProvider();
using (var scope = provider.CreateScope())
{
var dbContext = scope.ServiceProvider.GetRequiredService<TestDbContext>();
dbContext.Posts.Add(new Post() { Id = 1, Author = "test", Title = "test", PostedAt = DateTime.UtcNow });
dbContext.SaveChanges();
var post = dbContext.Posts.Find(1);
post.Author = "test2";
dbContext.SaveChanges();
dbContext.Posts.Remove(post);
dbContext.SaveChanges();
}
輸出結果(輸出結果的如果資料為 null 就會被忽略掉,所以對於新增的資料實際是沒有原始值的,對於刪除的資料沒有新的值):
More
EF Core 5 還有很多新的特性,有需要的小夥伴可以看一下官方文件的介紹~
上述原始碼可以在 Github 上獲取 https://github.com/WeihanLi/SamplesInPractice/blob/master/EF5Samples/SaveChangesInterceptorTest.cs